Circuit for simulating reverberation in electronic organs

Abstract

In an electronic organ system having a plurality of tone generators one for each note to be sounded, and a time constant circuit for establishing first and second decay characteristics for each note, the first of which has a longer decay period than the second, a key-down detector for sensing the operated condition of any key of the keyboard, and a circuit operative in response to the key-down detector to cause the sounded notes to have the longer decay characteristic so long as any key of the keyboard is depressed and to cause the sounded notes to have the shorter decay characteristic when all keys are released, for producing a pseudo-reverberation effect.

I claim: 
     
       1. In an electronic organ having a keyboard, and a plurality of tone generators, one for each note to be sounded, a like plurality of time constant circuit means, one associated with each of said notes, for establishing a predetermined first decay characteristic for each note,   a key-down detector for sensing the key-down condition of any key of the keyboard,   a like plurality of auxiliary circuit means connected one to each of said time constant circuit means and to said key-down detector and operative in response to said key-down detector to cause the sounded notes to have said predetermined first decay characteristic so long as any key of the keyboard is in its key-down position and to cause the sounded notes to have a second decay characteristic having a decay period shorter than the decay period of said first decay characteristic when all keys of the keyboard are in the key-up position.   
     
     
       2. In an electronic organ having a keyboard and a plurality of tone generators one for each note to be sounded, a gating circuit for each of the notes for transmitting a sounded note to acoustic reproducing apparatus, and a time constant circuit associated with each gating circuit for establishing a predetermined decay characteristic for each note transmitted by the gating circuit, apparatus for improving the reverberation effect produced upon playing the organ, said apparatus comprising: a like plurality of auxiliary discharge circuits connected one to each of said time constant circuits, and   circuit means including a key-down detector operative to disable all of said auxiliary discharge circuits so long as any key of the keyboard is in its key-down position, and to enable all of said auxiliary discharge circuits when all of the keys of the keyboard are in the key-up position, said auxiliary discharge circuits when enabled being operative to shorten the decay period of said predetermined decay characteristic.   
     
     
       3. Apparatus according to claim 2, wherein each of said time constant circuits includes a capacitor, wherein individual ones of said gating circuits are actuable by a potential from a DC supply voltage upon depression of a corresponding one of said keys and upon actuation charges the capacitor of the associated time constant circuit to substantially the potential of said supply voltage,   wherein each of said auxiliary discharge circuits includes a resistor connectable between one terminal of said capacitor and a second source of voltage having a lower potential than the potential of said DC supply voltage, and   wherein said key-down detector is connected to all of the keys of the keyboard and is operative when all keys are in the key-up position to connect all of said auxiliary discharge circuits to said second source of voltage.   
     
     
       4. In an electronic organ having a keyboard, a plurality of tone generators one for each note to be sounded, a like plurality of gating circuits, one for each of said tone generators, for transmitting a sounded note to acoustic reproducing apparatus, and a time constant circuit including a capacitor associated with each gating circuit for establishing a first decay characteristic for the note transmitted by the gating circuit, and wherein individual ones of said gating circuits are actuable by a potential from a DC voltage source upon closure of a corresponding keyswitch of said keyboard and upon actuation charges the capacitor of the associated time constant circuit to substantially the potential of said source voltage, apparatus for improving the reverberation effect produced upon playing the organ, said apparatus comprising: a like plurality of auxiliary discharge circuits connected one to the capacitor of each of said time constant circuits for establishing, when enabled, a second decay characteristic for a respective note, which second decay characteristic has a shorter decay period than said first decay characteristic, and   circuit means connected to all of said auxiliary discharge circuits and including a key-down detector connected to all of said keyswitches operative in response to any key of the keyboard being in its key-down position to disable all of said auxiliary discharge circuits, and operative in response to all of the keys of the keyboard being in the key-up position to enable all of said auxiliary discharge circuits to thereby establish said second decay characteristic.